The illumination of a car is a very critical factor as the car is driven at night. However, in general, the light of a car is not so great so that the driver can clearly see the front end view.
Thereby, there are many cars which is added some other lights for improving this defect, for example, HID lights. However, HID light can not used in fog or rainy day, even in fog or rainy day, the HID light becomes worse. Moreover, the HID light is too expensive to be accepted by users.